The new couple was first pictured together last month, strolling hand-in-hand after enjoying a dinner date near Williams' home in Brooklyn, and she showed her support for her new beau on Wednesday by joining him for his new film's premiere at the Ziegfeld Theater.

The Brokeback Mountain star avoided the media by skipping the red carpet, but she took a seat beside Segel for the Tribeca Film Festival screening and joined the cast at an after party at the Museum of Modern Art.

A source tells UsMagazine.com, "Michelle was really sweet but her usual shy self in crowds - she stayed close to Jason and only really engaged in conversation with people that she knew. Jason would put his arms around her waist and they gave each other a few sweet pecks - they definitely seemed to have a physical chemistry."

Segel recently confirmed he was dating Williams, telling news show Extra, "I think we would just very much like to be happy. That's all I'm going to say about it."

The My Week With Marilyn beauty was previously engaged to late actor Heath Ledger, the father of her six-year-old daughter Matilda.

Photo Credits: PR Photos

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